Kenshiro from Hokuto no Ken series. This character in manga and anime is taken so seriously that ended up being a parody of the manly man trope. This hulky guy is so over the top that torn apart his shirt everytime He charges up his anger and bulk up the muscular mass.
It's really hard for me to really think about a manly man when it comes to anime, I'm not really used to see them on the types of anime that I watch, lol. But if I had to pick one it would be Kanou Somuku from Okane ga Nai. I watched this one a few years ago, but I remember that he was just so big and manly, almost scary, lol.